adding a battery did nothing

[mazzasec 5,000+ posts]

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I am running a 250amp alternator stock upfront and 3 off brand batteries in the rear. With 2 batteries in it would go to 11.7-8 full tilt. I then added a 3rd one and it drops to like 11.8-9 full tilt.

Why didnt I gain anything from 2 going to 3 batteries

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[Einzee 10+ year member]

Are your batts balanced? One low one will do what you are experiencing. Maybe your voltage regulator in the alt needs a boost?

 

[Supergumby5000 5,000+ posts]

are you doing these tests at idle or while driving?

 

[keitare]

Maybe somethings wrong with your alt?

 

[mazzasec 5,000+ posts]

At idle

 

[Supergumby5000 5,000+ posts]

At idle

well, if you are expecting to be able to rest at idle on a 14.4volt system full bore with a single alternator, keep dreaming.

you are only charging at 150amps (ish) at idle, as soon as your batteries are drained, your ******* juice straight from that 150 amp source.

 

[mazzasec 5,000+ posts]

well, if you are expecting to be able to rest at idle on a 14.4volt system full bore with a single alternator, keep dreaming.
you are only charging at 150amps (ish) at idle, as soon as your batteries are drained, your ******* juice straight from that 150 amp source.

I think you read the post wrong. What I was saying is when I had 2 batteries in the rear it would drop to like 11.8 at full tilt. I then added a 3rd one hoping it wont drop below 12.2-3 at full tilt but for some odd reason my voltage drops are the same with 2 batteries and 3 batteries.

 

[Supergumby5000 5,000+ posts]

I think you read the post wrong. What I was saying is when I had 2 batteries in the rear it would drop to like 11.8 at full tilt. I then added a 3rd one hoping it wont drop below 12.2-3 at full tilt but for some odd reason my voltage drops are the same with 2 batteries and 3 batteries.

thats because your alternator cant keep up.

regardless of how large your battery bank is, as soon as its drained, your system is only as good as your alternator.

You could put 300 batteries in your truck, but as soon as they are drained, your gonna be right at 11.8 volts again. Sure, you'll keep charge longer, but as soon as you get to that thresh hold, yer gonna be at a low voltage.

 

[smoka 10+ year member]

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I am running a 250amp alternator stock upfront and 3 off brand batteries in the rear. With 2 batteries in it would go to 11.7-8 full tilt. I then added a 3rd one and it drops to like 11.8-9 full tilt.

Why didnt I gain anything from 2 going to 3 batteries

Some details would be nice.

How many watts is that amp putting out?

If you are using more power than the alt can generate, then all the extra batts are going to do is buy you more time until the voltage drop.

Lets pretend your alt is running maxed out at a constant 250a. That means at 14v it can produce 3500w of power, at 12v it drops to 3000w of power.

At an estimated 75% efficiency, that means if your amp is wired to output more than 2250w, then you are using more power than you can produce which means its only a matter of time before you drain your batts and fall under 12v.

Now those are just general numbers to give you an idea whats going on. But since music is dynamic you will not be maxing out your amp power which means that batts might get to charge but not much.

 

[smoka 10+ year member]

dam gumby you beat me to it.

 

[Supergumby5000 5,000+ posts]

dam gumby you beat me to it.

yeah, but you explained it better. I was lazy //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[loopkiller 10+ year member]

What are the open circuit resting voltages of those batteries and which brand/model?

 

[mendon mafia 10+ year member]

Adding Batteries should definitely help with voltage drops. Its not like hes playing 3k tones all day long (i hope not at least) so the alt should have plenty of time on average to charge the batts up to a reasonable voltage.

i used to only have a 200 amp alt and stock battery and my voltage used to dip into the high 10's at full tilt.

added an spv70 voltage never dropped below 11.5

added a second spv70 voltage stays in the 12.5-13 range all day long at full tilt.

Im running an at3000.1d @ .5 ohm so about 4k+ rms. but i never play tones, only music so on average i probably only draw about 2000 watts continuously. but my alt has no problem charging the system as long as i dont play it full tilt for hours/days on end on bass heavy tracks.

but to answer you question about why you didnt gain anything, Make sure all your connections are tight including your grounds and all wires associated with your charging system. if that dos not help then your batteries are probably not holding a charge and should be replaced.

 

[Supergumby5000 5,000+ posts]

Adding Batteries should definitely help with voltage drops. Its not like hes playing 3k tones all day long (i hope not at least) so the alt should have plenty of time on average to charge the batts up to a reasonable voltage.
i used to only have a 200 amp alt and stock battery and my voltage used to dip into the high 10's at full tilt.

added an spv70 voltage never dropped below 11.5

added a second spv70 voltage stays in the 12.5-13 range all day long at full tilt.

Im running an at3000.1d @ .5 ohm so about 4k+ rms. but i never play tones, only music so on average i probably only draw about 2000 watts continuously. but my alt has no problem charging the system as long as i dont play it full tilt for hours/days on end on bass heavy tracks.

but to answer you question about why you didnt gain anything, Make sure all your connections are tight including your grounds and all wires associated with your charging system. if that dos not help then your batteries are probably not holding a charge and should be replaced.

first off, he is talking about being at idle.

second off, his amp makes your amp look like a little girl.

batteries wont make your car magically have a better resting voltage unless they are modded for a higher voltage (16v, etc). Batteries dont charge themselves. They will only make the rate at which you drop voltage decrease.

 

[DumpinTreos 10+ year member]

How many runs of wire are you using? Maybe that is why the alt can't catchup